Controllable underwater drainage apparatus

ABSTRACT

An underwater drainage apparatus of the type having integrally formed therein a trap chamber and an underwater seal chamber and also a pressure regulating manometer chamber. A baffle arrangement is provided for preventing loss of liquid from the underwater seal chamber and/or the pressure regulator chamber; and a fluid flow meter is provided for measuring air flow through the underwater seal chamber and/or through the pressure regulator chamber. A special pediatric compartment is formed in the trap chamber.

. United States Patent 1111 3,559,647

[72] Inventors Robert E. Bidwell [56] References Cited m a; 198 L l l d UNITED STATES PATENTS I my IS in, os yn, ong s an Leonard D. KuflLwoodmere; Edward J. l[:llreman 128/214 "sustain Smithmwn NDY. yman 128/214 3,279,467 /1966 Hofstra et al. 128/276 [21] AppLNo 734,645 3 345 980 10 1967 [22] Filed Junes I968 Coanda 128/2 Patented Feb. 3,363,626 l/1968 Bidwell et al. 128/276 Assignee Said Bidwell and said Mishkin assignors to 3363627 H1968 Bidwe 28/276 D k t I I L 3,374,939 3/1968 McMenimen 128/295 e 3,381,687 5/1968 Andersen etal. 128/276 Island, NY 3,392,580 7/1968 Bain et a1 73/200 8 3,436,500 4/1969 Culbert et a] 73/401 Primary Examiner-Charles F. Rosenbaum Attorney-Larson, Taylor & Hinds [54] CONTROLLABLE UNDERWATER DRAINAGE ABSTRACT: An underwater drainage apparatus of the type APPAFATUS having integrally formed therein a trap chamber and an un- 38 clalmss Drawing derwater seal chamber and also a pressure regulating [52] U.S.Cl 128/276, manometer chamber. A baffle arrangement is provided for 73/200, 73/401, 137/176, 141/59 preventing loss of liquid from the underwater seal chamber [51] Int. Cl ,i A6lm l/00 and/or the pressure regulator chamber; and a fluid flow meter Field of Search, 128/275. is provided for measuring air flow through the underwater seal 276, 277, 295, BAG( Digest), H-L(Digest); 137/176; 141/59; 73/401--402, 200. 211. 216

chamber and/or through the pressure regulator chamber. A special pediatric compartment is formed in the trap chamber.

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INVENTORS ROBERT E. BIDWELL SIDNEY MISHKIN BY If ATTORNEYS CONTROLLABLE UNDERWATER DRAINAGE APPARATUS FIELD OF THE INVENTION This invention relates to drainage apparatus of the type disclosed in our previous Pat. Nos. 3,363,626 and 3,363,627 for draining fluid from a cavity, and in particular to improvements in such apparatus.

BACKGROUND OF THE INVENTION Our previous Pat. Nos. 3,363,626 and 3,363,627, both issued Jan. l6, I968, include a brief explanation of the lung structure and of the human breathing function. They discuss also both the previously known three-bottle underwater drainage system and also the new and improved unitary drainage apparatus and system disclosed and claimed therein. For purposes of brevity, reference may be made to those previous patents for such basic explanations.

However, in the use of the underwater drainage unit, additional problems have been uncovered. As mentioned in the said previous patents, during normal operation of the unit, bubbles pass through both the pressure regulator chamber and the underwater seal chamber. One problem has been loss of liquid from the pressure regulator-chamber and/or from the underwater seal chamber due to this bubbling. It must be remembered that this bubbling can become very vigorous such that the rising bubbles carry the liquidnpwandly with them in a manner not unlike that of a geyser.

Another problem has been a need for greater control. The

previous structure gives an indication of the difference in pressure across the pressure regulator chamber and .also across the underwater seal chamber. However, once all the liquid intany U-tube has been pulled upwardly intoone of the two columns, a further increase in the force creating the pressure differential does not actually change thefidifference in pressure across the U-tube. Rather, it only increases the rate of gas flow (bubbling through the column containing the liquid. Thus,

since at various times during the operation of the underwater seal apparatus both chambers are bubbling, that is, both are operating at a maximum pressure differentiahit can be seen that knowledge of the pressure differential does not give a complete and true picture pf the actual conditions existing in sflrp t 1*,

' Another problerrihas been the inability to accurately determine the level .of liquid present in a column of a manometer when bubbles are passing vigorously therethrough.

Still another problem has been the inability to utilize this type of underwater seal apparatus for pediatric uses. For normal adult use the trap chamber must be large enough to collect a suflicient quantity of fluids, "for example, 3000 cubic centimeters. In any practical construction of a 3000 cubic centimeter trap chamber, graduations are meaningless below increments of 5 or IQ cubic centimeters. However, this is insufficient for pediatric uses wherein it must be possible to determine with some degree of accuracy each single cubic centimeter of accumulated liquid.

SUMMARY OF THE INVENTION The purpose of the present invention is to provide a new an improved underwater drainage apparatus which overcomes problems encountered in the use of previous underwater drainage apparatus.

To fully appreciate the significance of the present invention, it is necessary to understand additional features concerning the operation of the underwater drainage apparatus.

The underwater seal chamber serves several purposes, one of which is to prevent atmospheric air and evacuated gases from passing back into the pleural cavity. Another purpose is to provide a constant pressure head against which the drainage force (either suction applied by a pump and/or positive, pressure in the pleural cavity of the patient during expiramust act. This second purpose is fulfilled by keeping relatively constant the quantity of liquid forming the underwater seal ln our previous Pat. No. 3,363,327, the phenomenon of compliance was discussed. For example compliance could occur as the patient expanded his pleural cavity by move: ment of his rib cage and his diaphragm muscles) if the lung failed to expand with the cavity, owing to an obstruction in the patients air passage." Compliance manifests itself in the drainage apparatus by a rapid rise of liquid in the column of the underwater seal chamber adjacent the trap chamber. In one of our said previous patents a reservoir is provided for collecting liquid which rises in this column. Howev er, if this condition persists, bubbles will flow upwardly through the column of liquid and create a spray which will carry a substantial amount of liquid from the underwater seal over to the trap chamber, notwithstanding the provision of an enlarged reservoir at the top of the seal chamber.

Thus, according to one feature of the present invention there is provided an arrangement for preventing liquid sprayed upwardly in the underwater seal chamber from carrying over into the trap chamber. In a preferred embodiment of the present invention this result is obtained by placing a baffle arrangement in the path of the upwardly moving spray to catch the spray and direct the liquid downwardly and by placing the opening to the trap chamber away from the path of the spray. With this arrangement, when the momentum of the spray is eliminated by engagement with the baffle arrangement, the liquid falls downwardly back into the seal chamber, while the gases continue to move through the said opening into the trap chamber.

When a vacuum pump is attached to the drainage apparatus, the pressure regulator chamber is often employed to regulate the pressure to be applied on the side of the underwater seal chamber closest to the vacuum pump. For example, assume that it is desired to keep the common space above the leg of the pressure regulator chamber opposite from atmosphere and the leg of the underwater seal chamber opposite from atmosphere and the leg of the underwater seal chamber opposite from the trap chamber at a vacuum of -20 centimeters of water. The pump itself will normally be capable of pulling a vacuum much greater than the desired -20 centimeters so-that the maximum vacuum which the pump is capable of pulling must be reduced to the desired level by the pressure regulator. The pressure regulator chamber is filled with an amountof water such that when all of the water is located in the leg of the pressure regulator chamber closest to the pump, it will be at a height of 20 centimeters. Now the pump is turned on until the liquid in the leg of the pressure regulator chamber closest to the pump, does in fact rise to a level of 20 centimeters. Further pumping capacity will not further increase the vacuum in the said common space. Rather, it will draw air from the atmosphere through the pressure regulator chamber and into the pump. Meanwhile, assuming that the pressure in the pleural cavity is greater than -20 centimeters of water, the liquid in the underwater seal er will also in th o umn openin n o the ommon space. If the pressure in the pleural cavitycxceeds-20 centimeters of water by at least the maximum height of the water in the underwater seal chamber, bubbles of gas derived from the pleural cavity will pass upwardly through this column and into the said common space. Thus, it should be kept in mind that under some operating conditions, bubbles pass upwardly through both the pressure regulator chamber and the underwater seal chamber.

The P i n lykse Esq asset ejtssn sn of gas. for example, one cubic foot per minute. If the patients pleural cavity has no leaks to admit air therein the quantity of gas evacuated by the pump will be supplied entirely by the pressure regulator chamber and considerable bubbling will occur in this chamber. However, if a leak exists in the pleural cavity so that air is admitted into the cavity, the underwater seal will bubble and the bubbling through the pressure regulator chamber will be correspondingly reduced. It is important for the physician to know the amount of air leakage into the pleural cavity and also to know that the pump is capable of maintaining a sufficient degree of vacuum within the plueral cavity. Obviously, if the pressure conditions within the pleural cavity approached atmospheric, the patient would be unable to breathe and the physician must be made aware of any such approaching condition.

The foregoing problems are met according to the present invention by providing an airflow meter in the pressure regulator chamber and the underwater seal chamber. By reading the degree of bubbling through the underwater seal chamber the physician can determine the precise amount of leakage through the pressure regulator chamber. The physician can then be assured that the pump is maintaining the proper vacuum conditions and that the entire demand of the pump. i.e. one cubic foot per minute, is not being satisfied through the pleural cavity.

In a preferred embodiment of the invention, these flow meters each take the form of a plurality of slots arranged such that as the airflow is increased, the number of slots through which the airflow passes is increased.

As discussed above, bubbling of air through a liquid tends to carry the liquid upwardly in a manner not unlike that of a geyser. This has presented a problem in drainage apparatus of the present type in that the water bubbling through the pressure regulator chamber has tended to continue its upward movement into the pump. This, of course, is a considerable disadvantage since the liquid could cause erosion of the pump. Further the reduction in water level in the pressure regulator results in a corresponding reduction in the vacuum.

Thus, another feature of the present invention is a bafile arrangement for preventing the water which rises in the pressure regulator chamber from being carried into the pump. In a preferred embodiment of the invention this arrangement takes the form of a baffle means located in the path of the stream of bubbles so that the rising water engages the baffle means where it loses its momentum, after which it falls back into the pressure regulator chamber while the gas continues its movement into the pump,

The bubbling in the column of the pressure regulator chamber closest to the pump also presented the disadvantage that it was virtually impossible to determine with accuracy the level of the liquid in that column.

Thus, according to another feature of the present invention the column of the pressure regulator chamber closest to the pump comprises two portions in fluid communication with each other wherein the flow of bubbles is limited to only one of the two portions so that the other remains calm. The level of the liquid in the column of the pressure regulator closest to the pump can then be accurately determined by observing the calm chamber.

According to another feature of the present invention the trap chamber of the apparatus is provided with a special pediatric compartment having an opening beneath the main inlet to the trap chamber so that liquid entering the trap chamber will first collect in the pediatric compartment. This compartment will be sufficiently small in cross section so that fluid accumulation therein could be measured in increments of one cubic centimeter. This special compartment could be arranged so that after it became full, additional liquid entering the trap chamber would flow to the remaining portion of the trap chamber.

Thus, it is an object of this invention to provide a new an improved underwater drainage apparatus.

It is a further object of this invention to provide a drainage apparatus, the operation of which can be controlled with greater accuracy than has been possible heretofore.

It is another object of this invention to provide, in an underwater drainage apparatus, a means for measuring the flow of air through the apparatus.

It is still another object of this invention to provide, in underwater drainage apparatus a means for preventing spill-over of liquid from one chamber to an adjacent chamber.

It is still another object of this invention to provide a means for easily determining the level of liquid in a chamber through which air is bubbling.

lt.is still another object of this invention to provide a means for adapting an adult drainage apparatus for use in pediatric applications.

Other objects and the attendant advantages of the present invention will become apparent from the detailed description to follow together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS There follows a detailed description together with accompanying drawings of a preferred embodiment of the invention. However it is to be understood that the invention is capable of numerous modifications and variations apparent to those skilled in the art within the spirit and scope of the invention.

In the drawings:

FIG. I is a sectional view taken through the center plane of an underwater drainage apparatus constructed according to the present invention.

FIG. 2 is a horizontal sectional view taken along line 2-2 of FIG. I.

FIG. 3 is a horizontal sectional view taken along line 3-3 of FIG. 1.

FIG. 4 is a horizontal sectional view taken along line 4-of FIG. 1.

FIG. 5 is a horizontal sectional view taken along line 5-5 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, there is shown an improved drainage apparatus 10 constructed in accordance with the present invention. Although the method for making the apparatus does not form a part of the present invention, it will be noted that the apparatus could be moulded in two separate halves, which halves would be joined along the center plane on which FIG. I is taken. In this case FIG. 1 would represent one-half of the apparatus wherein the sectional lines represented the surface to be joined to the mating half, and wherein the plain areas represent spaces in the finished apparatus.

The apparatus could be constructed with its two large sides as plane surfaces wherein the parts shown in cross section in the drawings would be ribs extending inwardly from the plane sides. However, in a preferred embodiment of the invention, as is evident from FIGS. 2 through 4, the parts shown in cross section in FIG. I are formed as indentations from the outermost sides of the apparatus, which indentations join to form a thin seam between the various chambers along the center plane of the apparatus. However, whether scams or ribs are used, for purposes of convenience, the areas between the various chambers will be referred to hereinafter as partitions? Referring now to FIG. 1 there is shown an improved underwater drainage apparatus I0 having a trap chamber 11, an underwater seal chamber 12 comprising a first column 12a and a second column 12b, and a pressure regulator chamber 13 having a first column 13a and a second column formed in two portions, namely 13b and 13c. The apparatus is completely enclosed except for an opening 14 adapted to be connected to the pleural cavity of the patient, an opening I5 adapted to be connected to a vacuum source and an opening 16 to atmosphere.

One feature of the present invention includes a pediatric collection compartment formed by partition 20 in the main trap chamber 11. An upper portion 20a of the partition 20 and a drip ledge 22 deflect the incoming liquid into the pediatric collection compartment 21. The main feature of compartment 21 is that it is of a small enough cross section so that the amount of liquid collecting therein can be readily detennined in increments of one cubic centimeter. In a preferred embodiment of the invention this compartment will hold 250 cubic centimeters of liquid after which additional liquid will simply flow over the upper portion 200 and into the main portion of the trap chamber 11 which would normally be designed to hold approximately 3000 cubic centimeters.

Trap chamber 11 is also provided with a solid cross-rib 24 designed to strengthen the trap chamber to prevent implosion. This rib 24 separates the bottom of the trap chamber into two parts 23:: and 23b. 23a would fill up first after which further liquid would flow over 24 to 231).

The underwater seal chamber 12 is formed by partitions 30, 31 and 32 which form first and second columns 12a and 12h communicating through passage 33 at their lower ends.

At the upper end of column 120 there is provided an enlarged reservoir 35 with a recessed bottom 36. These elements serve the same purpose as the enlarged reservoir and recess shown in our previous Pat. No. 3,363,627.

In addition, there is provided at the upper end of column 12a a means for preventing liquid surging upwardly in column 12a (e.g. during compliance) from entering the trap chamber 11. For this purpose there is provided a separation chamber 39 which lies in the path of, and thus is engaged by the upwardly surging column of liquid. As the liquid engages the walls of this chamber it loses its momentum and falls downwardly while the upwardly surging gases continue to travel through an upper opening 40 and through the area 35 to the opening 34 leading to the trap chamber 11. To assist this upward movement of surging gas and liquid, the area 35 is spaced from the main portion of column 120 by a partition 37. Moreover, the upper and lower openings 40 and 38 are inclined downwardly towards the area 35. Thus, while most of the liquid entering chamber 39 will fall down column 12a, some liquid will enter the upper opening 40 and fall into the area 35. However, since the momentum of the liquid at this point has been substantially reduced, it will fall downwardly under the force of gravity to recess 36 rather than pass with the gases through the opening 34.

An important feature of the present invention is the gas flow meter 45 for determining the flow rate of gas passing through the underwater seal chamber. Obviously, for gas to flow upwardly in column 12b, the level of liquid in 120 must be at the bottom thereof. The flow meter comprises a series of openings 46a, 46b, 46c, 46d, formed in the web partition member 47. Of course more openings could be employed if desired. Gas bubbling through opening 46a would indicate a predetermined rate of gas flow. As the gas flow increased, bubbling would be visible through the two openings 46a and 46b. A further increase in the bubbling rate would be indicated by bubbles passing through openings 46a, 46b and 46c. In a like manner additional gas flow would cause bubbling through all four openings 4611 through 46d. This type of flow meter would be of significant importance for diagnosing certain types of conditions such as air loss from the patients lung into his pleural cavity through a bronchopleural fistula. For example, opening 46a may represent a loss of 2 liters per minute while flow through openings 46b and 46c may represent an airflow of 4 liters per minute and 8 liters per minute respectively. Air flow through opening 46d would indicated a flow greater than 8 liters per minute. 2 liters per minute is believed to be satisfactory. A loss of 4 liters per minute should be called to the doctor's attention and a loss of 8 liters per minute might well represent an emergency situation.

The column 12b includes an enlarged reservoir area 12c to hold the water in the underwater seal in the event of violent bubbling of air through column 12b, as might occur in the case of a very large bronchopleural fistula.

The portion of the apparatus to the left of partition 32 (as shown in FIG. 1) represents the pressure regulator chamber 13 having a first column 13a with its upper end exposed to atmosphere and a second column which comprises two portions 13b and 13c, each of which is exposed at its upper end to the pressure at vacuum opening 15. Thus, the upper ends of portions 13b and 13c together with the upper portion of column 12b form a common space exposed to the pressure at vacuum opening 15.

The purpose of the two portions 13b and 136 is two-fold. The main purpose is to confine the bubbles rising through the pressure regulator chamber to the portion 13b so that the liquid rising with the air bubbles will engage a main baffle 53 which will deflect the liquid downwardly into either portion l3h or 134' after which the gas would continue its upward movement to the opening 15.

To assist in-confining the bubbles to portion 13b, the lower opening 52 connecting the two portions 13!) and [3c is directed downwardly between lower edge 50a of a partition 50 and a lower ledge 51. Thus, while portions 13b and 13c will tend to seek the same level, the bubbles will be confined to portion 13b.

In practice, water will flow clockwise around the partition 50 (as viewed in FIG, l)'forming a "racetrack like path of water. Much of the liquid engaging baffle 53 will fall into portion 130. However, since the level of liquid in cannot rise above the level of liquid in 13b then the level in 136 must go down and the additional liquid flows through opening 52 back into the portion 13b.

Another feature of the two portion arrangement is that it provides a calm portion 13c exposed to the same pressure as 13b but relatively clam as compared to portion 13b. Consequently, the level of liquid in the second column of the pressure regulator chamber 13 can be readily determined by noting the level of liquid in portion 13c.

In the event that some liquid does flow upwardly pass baffle 53, it will be engaged by a second baffle 54. Further upward flow of water is caught by a series of drip ledges 55a, 55b and 556.

An important feature of the present invention is the flow meter 60 which clearly and visually shows the rate of airflow upwardly through the second column of the pressure regulator chamber. REferring to FIGS. 1 and 4, this flow meter 60 comprises a web partition member 61 extending across the flow meter and having formed therein a plurality of airflow holes 62a, 62b, 62c and 62d. Of course the number, shape and/or size of the holes would depend upon the desired operating characteristics of the flow meter. A given force would be necessary to draw air through the hole 62a. A greater force would increase the volume of airflow so that bubbles passed through hole 62b as well as 62a. With still greater force the volume of airflow would increase until it flowed through openings 62cas well as opening 62a and 62b. Finally, still a greater force would cause further increase in the volume of airflow so that the air passed through all four openings including opening 62d. By way of example, assuming that the capacity of the pump attached to opening 15 is one cubic foot per minute, the openings could be designed to represent onefourth, one-half, threequarters and one cubic foot of airflow per minute. With this arrangement it would be possible merely by observing the airflow meter, to determine which portion of the total air passing to the vacuum pump through opening 15 is derived from the pressure regulator chamber 13 and which portion is derived from the pleural cavity through the underwater seal chamber 12.

The upper end of column 13a includes a funnel shaped opening 66 to facilitate placing water into the pressure regulator chamber. There is also formed a relief opening 65 to assure continued communication between column 13a and the atmosphere in the event that the opening 16 becomes obstructed.

The basic operation of the apparatus 10 is similar to the basic operation of the apparatus as described in our previous Pat. Nos. 3,363,626 and 3,363,627. The features of the present invention have not changed the basic operation of the apparatus. Rather, they have been designed for the purpose of increasing the efficiency, controllability and applicability of this type of apparatus. The effect that each of these individual features has on the basic operation is believed to be clear from the above description of the various features. However, for purposes of convenience, the operation of the invention will be briefly summarized at this point.

When the apparatus is to be used as a three-bottle apparatus, an amount of liquid is introduced into the pressure regulator chamber 13 through opening 16 which will give the desired vacuum after the pump is turned on; and a desired amount of liquid is introduced into the underwater seal chamber 12 through opening 15. Opening 14 is then connected to the pleural cavity of the patient and opening 15 is connected to a vacuum pump. The pump is then turned on gradually as the liquid rises in the second column of the pressure regulator chamber (portions 131; and 13c). As the capacity of the vacuum pump increases, the liquid rises in portions 13b and 13c until all of the liquid is contained in these portions. A further increase in the capacity of the pump will cause air bubbles to be drawn through opening 62a into the portion 13b and hence through the opening 15 to the vacuum pump. Any liquid rising with the bubbles will engage baffle 53 and fall downwardly. Meanwhile the liquid in the underwater seal chamber may rise in column 12b in which case bubbles will flow upwardly through opening 46a to the opening and hence to the vacuum pump.

The fluids (gases and liquids) coming from the patient enter the apparatus 10 at opening 14. Liquids fall into the compartment 21 as gases pass through the opening 34 and hence to the underwater seal chamber. Once the chamber 21 has been filled, additional liquid entering the opening 14 flows over the upper portion 200 of the partition into the first main portion 23a of trap chamber 11. When this fills, further liquid will flow over 24 into 2317.

If compliance" occurs within the pleural cavity of the patient, the absolute pressure in the trap chamber 11 could be reduced far below the absolute pressure in the vicinity of opening 15. Consequently, the liquid in seal chamber 12 will rise rapidly in column 120. As described in our previous Pat. No. 3,363,627, the compliance chamber 35 prevents much of this liquid from passing to the opening 34. However, in accordance with the present invention the spray of liquid carried upwardly by the bubbles will engage separation chamber 39 where it will lose its momentum and fall downwardly back to the column 12a or to the area 35.

When the patient is breathing normally, the liquid levels in the two legs of the underwater seal chamber will fluctuate in response to pressure fluctuations in the pleural cavity associated with normal breathing-assuming of course, that there is a suflicient amount of water in the underwater seal chamber so that bubbling does not commence when the pressure in the pleural cavity reaches its maximum value. With this in mind, it can be seen that these fluctuations serve as a diagnostic tool to indicate the presence of conditions such as emphysema and asthma which require that the patient work harder (create a greater negative pressure in the pleural cavity) in order to cause expansion of the lung. These conditions will be indicated by a larger than normal rise of the liquid in the leg of the underwater seal chamber in communication with the trap chamber during inspiration.

Although the invention has been described in considerable detail with respect to a preferred embodiment thereof it should be apparent that the invention is capable of numerous modifications and variations apparent to those skilled in the art without departing from the spirit or scope of the invention as defined in the claims.

We claim:

1. In a drainage device for draining fluids from a cavity comprising an inlet opening adapted to be placed in fluid communication with the cavity to be drained, a vacuum opening adapted to be placed in fluid communication with a vacuum source and with the inlet opening for drawing fluid from the cavity into the device, and a manometer for regulating the vacuum, said manometer comprising first and second columns in fluid communication with each other, said manometer adapted to receive a body of liquid within the first and second columns, the first column being exposed to atmosphere and the second column being exposed to the vacuum source; the improvement including, a measuring means formed in said manometer for measuring the rate of airflow therethrough, whereby when the pressure in the first column exceeds the pressure in the second column by a sufficient amount so that air bubbles can flow from said first column, said measuring means measures the rate of said airflow.

air bubbles can flow from said first column through said second column. said measuring means measures the rate of said airflow.

2. A drainage device as claimed in claim 1. wherein the said measuring means includes a gas flow meter. said meter comprising a partition member located in the interior of the manometer and having a plurality of holes formed therein. said holes being arranged such that as the said pressure differential force causing the bubbling increases. the number of holes through which air bubbles pass also increases.

3. A drainage device as claimed in claim 2, wherein the said partition member extends across the bottom of the said second column generally horizontally, and said holes are located progressively farther away from the first column, whereby air bubbles first pass through only the hole closest to the first column and whereby as the said force increases, air bubbles also pass through holes farther away from the first column.

4. A drainage device as claimed in claim 3, wherein said second column comprises two portions in fluid communication with each other at their upper ends, wherein both portions are exposed to the vacuum source, and including means for confining air bubbles to only one of said portions, whereby the liquid in the other portion remains relatively calm.

5. A drainage device as claimed in claim 3, including a baffle means for preventing liquid rising with the air bubbles from passing through the said vacuum opening.

6. A drainage device as claimed in claim 5. wherein said second column comprises two portions in fluid communication with each other at their upper ends and wherein both portions are exposed to the vacuum source, said baffle means comprising an arrangement for confining the air bubbles to only one of the two portions, and a baffle member located above the said one portion in the path of the rising bubbles whereby the liquid which rises with the bubbles engages the baffle member and falls downwardly as the air continues to flow towards the vacuum opening.

7. A drainage device as claimed claim 1, including a seal chamber having first and second columns in fluid communication with each other at their lower ends, said seal chamber forming a part of the fluid communication between the vacuum opening and the inlet opening, the first seal chamber column being in fluid communication with the cavity being drained and the second seal chamber column being in fluid communication with said vacuum source, and including a measuring means formed in the seal chamber for measuring the rate of gas flow through the seal chamber, whereby when the pressure in the first seal chamber column exceeds the pressure in the second seal chamber column by a sufficient amount so that gas bubbles can flow from .said first seal chamber through sad second seal chamber column, said seal chamber measuring means will measure the rate of said gas flow.

8. A drainage device as claimed in claim 7, wherein each of said measuring means comprises a flow meter comprising a partition member located in the interior of its respective chamber and having a plurality of holes formed therein, said holes of each flow meter being arranged such that in each chamber, as the associated pressure differential force causing the bubbling in that chamber increases. the number of holes through which the bubbles pass also increases.

9. A drainage device as claimed in claim 8, wherein the partition member in the manometer extends across the bottom of the second column generally horizontally, said holes being located progressively farther away from the first column, and wherein the partition member in the seal chamber extends horizontally across the bottom of the second COlllml'l of the seal chamber and wherein the holes are located progressively farther away from the first column of the seal chamber.

10. A drainage device as claimed in claim 9, wherein said second column of the manometer comprises two portions in fluid communication with each other at their upper ends. wherein both portions are exposed to the vacuum source, and including means for confining air bubbles to only one of said portions, whereby the liquid in the other portion remains relatively calm.

11. A drainage device as claimed in claim 9, including a baffle means for preventing liquid rising in the second column of the manometer with the air bubbles from passing through the said vacuum opening.

12. A drainage device as claimed in claim 11, wherein said second column of the manometer comprises two portions in fluid communication with each other at their upper ends and wherein both portions are exposed to the vacuum source, said baffle means comprising an arrangement for confining the air bubbles to only one of the two portions and a baffle member located above the said one portion in the path of the rising bubbles, whereby the liquid which rises with the bubbles engages the baffle member and falls downwardly as the air continues to flow towards the vacuum opening.

13. In a device for regulating the pressure within a cavity of a person, comprising a trap chamber and an underwater seal chamber, said trap chamber having located at its upper end an inlet opening and an outlet opening, said seal chamber also having located at its upper end an inlet opening and an outlet opening, the seal chamber inlet being in fluid communication with the trap chamber outlet, said trap chamber openings being separated from each other so that liquid received from the cavity can fall into the trap chamber while gas can pass through said trap chamber outlet into the seal chamber, and the seal chamber having first and second columns in fluid communication with each other at their lower ends, the seal chamber inlet being located at the upper end of the first column, whereby the first column is exposed to pressure conditions in the trap chamber, and the seal chamber outlet being located at the upper end of the second column, whereby the second column is exposed to pressure conditions other than that in the trap chamber; the improvement including, a measuring means formed in said seal chamber for measuring the rate of gas flow therethrough, whereby when liquid is placed in the seal chamber and the pressure in the first column exceeds the pressure in the second column by a sufficient amount so that gas bubbles can flow from said first column through Said second column, said measuring means measures the rate of said gas flow.

l4. in a device for regulating the pressure within a cavity of a person, according to claim 13, said trap chamber including a pediatric collection compartment and at said trap chamber including a pediatric collection compartment and at least one other collection compartment, the two compartments being located side by side and in fluid communication with each other only through an upper opening located at their upper ends, said pediatric collection compartment being located directly beneath the inlet opening to the trap chamber such that all liquid entering the trap chamber first enters the pediatric collection compartment, until the pediatric collection compartment is filled up to the upper opening, and after which additional liquid entering the trap chamber spills through the upper opening into the said other collection compartment, said pediatric collection compartment being of sufficiently narrow cross section such that the volume of liquid collected therein may be readily ascertained in increments of approximately one cubic centimeter.

15. A drainage device as claimed in claim 13, wherein the said measuring means includes a gas flow meter, said meter comprising a partition member located in the interior of the seal chamber and having a plurality of holes formed therein, said holes being arranged such that as the said pressure differential force causing the bubbling increases, the number of holes through which bubbles pass also increases.

16. A drainage device as claimed in claim 15, wherein the said partition member extends horizontally across the'bottom of the seal chamber at the bottom of the second column, said 10 holes being located progressively farther away from the said first column, whereby bubbles first pass through only the hole closest to the first column, and whereby as the said force increases, air bubbles also pass through the other holes.

17. A drainage device as claimed in claim 16, wherein said seal chamber also includes a baffle means for preventing liquid which rises with air bubbles in the first column of the seal chamber from being carried over into the trap chamber, whereby when the said other pressure exceeds the pressure in the trap chamber by a sufficient amount so that all the liquid in the seal chamber rises into the first column and air bubbles rise therein, the rising liquid will engage the baffle means and fall downwardly back into the seal chamber, as the bubbles continue to travel through the seal chamber inlet to the trap chamber.

18. A drainage device as claimed in claim 17, wherein the baffle means comprises a separation chamber located at the upper end of the first column directly above the first column, and including an enlarged upper reservoir immediately adjacent and in fluid communication with the separation chamber, and the said seal chamber inlet in fluid communication with the trap chamber being located on the side of the reservoir opposite from the separation chamber, whereby the gases which pass said bafi'le means pass through the enlarged reservoir to the trap chamber.

l9. A drainage device as claimed in claim 18, including a pair of vertically spaced openings between the first column and the reservoir, the upper of the two openings being positioned so that gases can pass therethrough to the trap chamber and so that some of the liquids which engage the baffle means can pass therethrough to the reservoir, and the lower of the two openings being positioned so that liquid in the reservoir can pass therethrough and rise with the bubbles to the separation chamber.

20. A drainage device as claimed in claim 18, including a manometer having first and second columns in fluid communication with each other at their lower ends, the first manometer column being exposed to atmosphere and the second manometer chamber being in fluid communication with the second column of the seal chamber, the two second columns thereby forming a common space exposed to said other pressure conditions and a vacuum opening from said common space adapted to be connected to a vacuum source.

21. A drainage device as claimed in claim 20, wherein said second column of the manometer includes 20, manometer baffle means which prevents liquid, which may rise in the second column when the said other pressure is less than atmospheric pressure by a sufficient amount, from passing through said vacuum opening of the common space to the vacuum source.

22, A drainage device as claimed in claim 21, wherein said second column of the manometer comprises two portions in fluid communication with each other at their upper ends and wherein both portions are exposed to the vacuum source, said manometer baffle means comprising an arrangement for confining the air bubbles to only one of the two portions and a manometer baffle member located above the said one portion in the path of the rising bubbles, whereby the liquid which rises with the bubbles engages the baffle member and falls downwardly as the air continues to flow towards the vacuum opening.

23. In a drainage device for draining fluids from a cavity comprising, an inlet opening adapted to be placed in fluid communication with the cavity to be drained, a vacuum opening adapted to be placed in fluid communication with a vacuum source and with the inlet opening for draining fluids from the cavity into the device, and a manometer for regulating the vacuum, said manometer comprising a first and a second column, said manometer being adapted to receive a body of liquid therein within the first and second columns, the first column being exposed to the atmosphere and the second column being exposed to the vacuum source; the improvement, wherein said second column includes a baffle means for catching liquids splashed upwardly with the air bubbles which pass through the manometer when the vacuum source pressure is lower than atmospheric pressure by a sufficient amount, said baffle means being arranged to direct the liquid downwardly back into the second column while permitting air to pass by said baffle means, whereby the splashed liquid remains in the second column while the air is permitted to pass through to the vacuum opening, said second column comprising two vertically extending portions separated by a partition and in fluid communication with each other via upper and lower openings above and below the partition, respectively, and wherein both portions are exposed to the vacuum source, said partition arranged such that air bubbles from the first column are directed substantially up into only one of the two portions, said baffle means comprising a bafi'le member located above the said one portion in the path of the rising bubbles, such that the liquid which rises in the said one portion with the bubbles engages the baffle member and falls downwardly as the air continues to float toward the vacuum source, some of this liquid falling into the second portion, and wherein an amount of makeup water flows from the second portion to the first portion through the lower opening, such that flow of at least some liquid is created around the partition, up in the first portion, through the upper opening, and down in the second portion through the lower opening.

24. A drainage device as claimed in claim 23, said lower opening being shaped to prevent the passage of air bubbles therethrough from the first portion to the second portion.

25. A drainage device as claimed in claim 24, wherein the said lower opening is directed downwardly from said first portion to said second portion.

26. A drainage device as claimed in claim 23, wherein said manometer includes a measuring means for measuring the rate of flow of air through the manometer.

27. A drainage device as claimed in claim 23, including a seal chamber having first and second columns in fluid communication with each other at their lower ends, said seal chamber forming a part of the fluid communication between the vacuum opening and the inlet opening, the first seal chamber column being in fluid communication with the cavity being drained and the second seal chamber column being in fluid communication with said vacuum source, and including a measuring means formed in the seal chamber for measuring the rate of gas flow through the seal chamber, whereby when the pressure in the first seal chambercolumn exceeds the pressure in the second seal chamber column by a sufficient amount so that gas bubbles can flow from said first seal chamber through said second seal chamber column, said seal chamber measuring means will measure the rate of said gas flow.

28. A drainage device as claimed in claim 27, including a measuring means in the manometer for measuring the rate of flow of air passing therethrough.

29. A drainage device as claimed in claim 28, wherein each of said measuring means comprises a flow meter comprising a partition member located in the interior of its respective chamber and having a plurality of holes formed therein, said holes of each flow meter being arranged such that in each chamber, as the associated pressure differential force causing the bubbling in that chamber increases, the number of holes through which the bubbles pass also increases.

30. A drainage device as claimed in claim 29, wherein the partition member in the manometer extends across the bottom of the second column generally horizontally, said holes being located progressively farther away from the first column, and wherein the partition member in the seal chamber extends horizontally across the bottom of the second column of the seal chamber, and wherein the holes are located progressively farther away from the first column of the seal chamber.

31. In a device for regulating the pressure within a cavity of a person comprising a trap chamber and an underwater seal chamber, said trap chamber having located at its upper end an inlet opening and an outlet opening, said seal chamber also having located at its upper end an inlet opening and an outlet opening, the seal chamber inlet being in fluid communication with the trap chamber outlet, said trap chamber openings being spaced from each other so that liquid entering the inlet opening can fall downwardly in the trap chamber while gases entering the inlet opening may normally pass through the said chamber outlet to the seal chamber, said seal chamber having first and second vertically extending columns in fluid communication with each other at their lower ends, the seal chamber inlet being located at the upper end of the first column, whereby the first column is exposed to pressure conditions in the trap chamber, and the seal chamber outlet being located at the upper end of the second column whereby the second column is exposed to pressure conditions other than that of the trap chamber; the improvement wherein, said first column includes a baffle means for catching liquids splashed upwardly with air bubbles which pass through the first column of the seal chamber during abnormal conditions when the said other pressure exceeds the trap chamber pressure by a sufficicnt amount, said baffle means being arranged to direct the liquid downwardly back into the first column while permitting gases to pass by said baffle means and to said trap chamber, the baffle means comprising an inverted cup-shaped separation chamber located at the upper end of the first column directly above the main portion of the first column, and including an enlarged upper reservoir immediately adjacent and in fluid communication with the main portion of the first column adjacent the separation chamber, and the said sealed chamber inlet in fluid communication with the trap chamber being located on the side of the reservoir opposite from the main portion of the first column, whereby the gases which pass said baffle means pass through the enlarged reservoir to the trap chamber.

32. A drainage device as claimed in claim 31, including a pair of vertically spaced openings between main portion of the first column and the reservoir, the upper of the two openings being positioned so that gases can pass therethrough to the trap chamber and so that some of the liquids which engage the baffle means can pass therethrough to the reservoir, and the lower of the two openings being positioned so that liquid in the reservoir can pass therethrough and rise with the bubbles to the separation chamber.

33. A drainage device as claimed in claim 31, including a manometer having first and second columns in fluid communication with each other at their lower ends, the first manometer column being exposed to atmosphere and the second manometer chamber being in fluid communication with the second column of the seal chamber, the two second columns thereby forming a common space exposed to said other pressure conditions and a vacuum opening from said common space adapted to be connected to a vacuum source.

34. A drainage device as claimed in claim 33, wherein said second column of the manometer includes a manometer baffle means which prevents liquid, which may rise in the second column when the said other pressure is less than atmospheric pressure by a sufiicient amount, from passing through said vacuum opening of the common space to the vacuum source.

35. In a drainage device for draining fluids from a cavity comprising an inlet opening adapted to be placed in fluid communication with the cavity to be drained, a vacuum opening adapted to be placed in fluid communication with a vacuum source and with the inlet opening for drawing fluids from the cavity into the device, and a manometer for regulating the vacuum, said manometer comprising first and second columns in fluid communication with each other, said manometer adapted to receive a body of liquid within the first and second columns, the first column being exposed to atmosphere and the second column being exposed to the vacuum source; the improvement wherein, said second column includes two portions in fluid communication with each other, said portions being arranged such that when the pressure of the vacuum source is reduced below atmospheric pressure by a sufficient amount so that air bubbles can pass from said first column upwardly through the second column, said bubbles are substantially confined to only one of said portions, whereby the other portion remains relatively calm so that the level of the liquid in the second column can be easily ascertained by observing the level of the liquid in the said calm other portion.

36. A drainage device as claimed in claim 35, wherein said two portions are positioned adjacent each other. separated by a partition which has formed therein an upper opening for said communication between the portions near their upper ends and a lower opening for said fluid communication between said portions near their lower ends.

37. A drainage device as claimed in claim 36, wherein said 

1. In a drainage device for draining fluids from a cavity comprising an inlet opening adapted to be placed in fluid communication with the cavity to be drained, a vacuum opening adapted to be placed in fluid communication with a vacuum source and with the inlet opening for drawing fluid from the cavity into the device, and a manometer for regulating the vacuum, said manometer comprising first and second columns in fluid communication with each other, said manometer adapted to receive a body of liquid within the first and second columns, the first column being exposed to atmosphere and the second column being exposed to the vacuum source; the improvement including, a measuring means formed in said manometer for measuring the rate of airflow therethrough, whereby when the pressure in the first column exceeds the pressure in the second column by a sufficient amount so that air bubbles can flow from said first column, said measuring means measures the rate of said airflow.
 2. A drainage device as claim 1, wherein the said measuring means includes a gas flow meter, said meter comprising a partition member located in the interior of the manometer and having a plurality of holes formed therein, said holes being arranged such that as the said pressure differential force causing the bubbling increases, the number of holes through which air bubbles pass also increases.
 3. A drainage device as claimed in claim 2, wherein the said partition member extends across the bottom of the said second column generally horizontAlly, and said holes are located progressively farther away from the first column, whereby air bubbles first pass through only the hole closest to the first column and whereby as the said force increases, air bubbles also pass through holes farther away from the first column.
 4. A drainage device as claimed in claim 3, wherein said second column comprises two portions in fluid communication with each other at their upper ends, wherein both portions are exposed to the vacuum source, and including means for confining air bubbles to only one of said portions, whereby the liquid in the other portion remains relatively calm.
 5. A drainage device as claimed in claim 3, including a baffle means for preventing liquid rising with the air bubbles from passing through the said vacuum opening.
 6. A drainage device as claimed din claim 5, wherein said second column comprises two portions in fluid communication with each other at their upper ends and wherein both portions are exposed to the vacuum source, said baffle means comprising an arrangement for confining the air bubbles to only one of the two portions, and a baffle member located above the said one portion in the path of the rising bubbles whereby the liquid which rises with the bubbles engages the baffle member and falls downwardly as the air continues to flow towards the vacuum opening.
 7. A drainage device as claimed claim 1, including a seal chamber having first and second columns in fluid communication with each other at their lower ends, said seal chamber forming a part of the fluid communication between the vacuum opening and the inlet opening, the first seal chamber column being in fluid communication with the cavity being drained and the second seal chamber column being in fluid communication with said vacuum source, and including a measuring means formed in the seal chamber for measuring the rate of gas flow through the seal chamber, whereby when the pressure in the first seal chamber column exceeds the pressure in the second seal chamber column by a sufficient amount so that gas bubbles can flow from said first seal chamber through sad second seal chamber column, said seal chamber measuring means will measure the rate of said gas flow.
 8. A drainage device as claimed in claim 7, wherein each of said measuring means comprises a flow meter comprising a partition member located in the interior of its respective chamber and having a plurality of holes formed therein, said holes of each flow meter being arranged such that in each chamber, as the associated pressure differential force causing the bubbling in the heat chamber increases, the number of holes through which the bubbles pass also increases.
 9. A drainage device as claimed in claim 8, wherein the partition member in the manometer extends across the bottom of the second column generally horizontally, said holes being located progressively farther away from the first column, and wherein the partition member in the seal chamber extends horizontally across the bottom of the second column of the seal chamber and wherein the holes are located progressively farther away from the first column of the seal chamber.
 10. A drainage device as claimed in claim 9, wherein said second column of the manometer comprises two portions in fluid communication with each other at their upper ends, wherein both portions are exposed to the vacuum source, and including means for confining air bubbles to only one of said portions, whereby the liquid in the other portion remains relatively calm.
 11. A drainage device as claimed in claim 9, including a baffle means for preventing liquid rising in the second column of the manometer with the air bubbles from passing through the said vacuum opening.
 12. A drainage device as claimed in claim 11, wherein said second column of the manometer comprises two portions in fluid communication with each other at their upper ends and wherein both portions are exposed to the vacuum source, said baffle means comprising an arrangement fOr confining the air bubbles to only one of the two portions and a baffle member located above the said one portion in the path of the rising bubbles, whereby the liquid which rises with the bubbles engages the baffle member and falls downwardly as the air continues to flow towards the vacuum opening.
 13. In a device for regulating the pressure within a cavity of a person, comprising a trap chamber and an underwater seal chamber, said trap chamber having located at its upper end an inlet opening and an outlet opening, said seal chamber also having located at its upper end an inlet opening and an outlet opening, the seal chamber inlet being in fluid communication with the trap chamber outlet, said trap chamber openings being separated from each other so that liquid received from the cavity can fall into the trap chamber while gas can pass through said trap chamber outlet into the seal chamber, and the seal chamber having first and second columns in fluid communication with each other at their lower ends, the seal chamber inlet being located at the upper end of the first column, whereby the first column is exposed to pressure conditions in the trap chamber, and the seal chamber outlet being located at the upper end of the second column, whereby the second column is exposed to pressure conditions other than that in the trap chamber; the improvement including, a measuring means formed in said seal chamber for measuring the rate of gas flow therethrough, whereby when liquid is placed in the seal chamber and the pressure in the first column exceeds the pressure in the second column by a sufficient amount so that gas bubbles can flow from said first column through said second column, said measuring means measures the rate of said gas flow.
 14. In a device for regulating the pressure within a cavity of a person, according to claim 13, said trap chamber including a pediatric collection compartment and at said trap chamber including a pediatric collection compartment and at least one other collection compartment, the two compartments being located side by side and in fluid communication with each other only through an upper opening located at their upper ends, said pediatric collection compartment being located directly beneath the inlet opening to the trap chamber such that all liquid entering the trap chamber first enters the pediatric collection compartment, until the pediatric collection compartment is filled up to the upper opening, and after which additional liquid entering the trap chamber spills through the upper opening into the said other collection compartment, said pediatric collection compartment being of sufficiently narrow cross section such that the volume of liquid collected therein may be readily ascertained in increments of approximately one cubic centimeter.
 15. A drainage device as claimed in claim 13, wherein the said measuring means includes a gas flow meter, said meter comprising a partition member located in the interior of the seal chamber and having a plurality of holes formed therein, said holes being arranged such that as the said pressure differential force causing the bubbling increases, the number of holes through which bubbles pass also increases.
 16. A drainage device as claimed in claim 15, wherein the said partition member extends horizontally across the bottom of the seal chamber at the bottom of the second column, said holes being located progressively farther away from the said first column, whereby bubbles first pass through only the hole closest to the first column, and whereby as the said force increases, air bubbles also pass through the other holes.
 17. A drainage device as claimed in claim 16, wherein said seal chamber also includes a baffle means for preventing liquid which rises with air bubbles in the first column of the seal chamber from being carried over into the trap chamber, whereby when the said other pressure exceeds the pressure in the trap chamber by a sufficient amount so that all the liquid in the seal chamber rises inTo the first column and air bubbles rise therein, the rising liquid will engage the baffle means and fall downwardly back into the seal chamber, as the bubbles continue to travel through the seal chamber inlet to the trap chamber.
 18. A drainage device as claimed in claim 17, wherein the baffle means comprises a separation chamber located at the upper end of the first column directly above the first column, and including an enlarged upper reservoir immediately adjacent and in fluid communication with the separation chamber, and the said seal chamber inlet in fluid communication with the trap chamber being located on the side of the reservoir opposite from the separation chamber, whereby the gases which pass said baffle means pass through the enlarged reservoir to the trap chamber.
 19. A drainage device as claimed in claim 18, including a pair of vertically spaced openings between the first column and the reservoir, the upper of the two openings being positioned so that gases can pass therethrough to the trap chamber and so that some of the liquids which engage the baffle means can pass therethrough to the reservoir, and the lower of the two openings being positioned so that liquid in the reservoir can pass therethrough and rise with the bubbles to the separation chamber.
 20. A drainage device as claimed in claim 18, including a manometer having first and second columns in fluid communication with each other at their lower ends, the first manometer column being exposed to atmosphere and the second manometer chamber being in fluid communication with the second column of the seal chamber, the two second columns thereby forming a common space exposed to said other pressure conditions and a vacuum opening from said common space adapted to be connected to a vacuum source.
 21. A drainage device as claimed in claim 20, wherein said second column of the manometer includes 20, manometer baffle means which prevents liquid, which may rise in the second column when the said other pressure is less than atmospheric pressure by a sufficient amount, from passing through said vacuum opening of the common space to the vacuum source.
 22. A drainage device as claimed in claim 21, wherein said second column of the manometer comprises two portions in fluid communication with each other at their upper ends and wherein both portions are exposed to the vacuum source, said manometer baffle means comprising an arrangement for confining the air bubbles to only one of the two portions and a manometer baffle member located above the said one portion in the path of the rising bubbles, whereby the liquid which rises with the bubbles engages the baffle member and falls downwardly as the air continues to flow towards the vacuum opening.
 23. In a drainage device for draining fluids from a cavity comprising, an inlet opening adapted to be placed in fluid communication with the cavity to be drained, a vacuum opening adapted to be placed in fluid communication with a vacuum source and with the inlet opening for draining fluids from the cavity into the device, and a manometer for regulating the vacuum, said manometer comprising a first and a second column, said manometer being adapted to receive a body of liquid therein within the first and second columns, the first column being exposed to the atmosphere and the second column being exposed to the vacuum source; the improvement, wherein said second column includes a baffle means for catching liquids splashed upwardly with the air bubbles which pass through the manometer when the vacuum source pressure is lower than atmospheric pressure by a sufficient amount, said baffle means being arranged to direct the liquid downwardly back into the second column while permitting air to pass by said baffle means, whereby the splashed liquid remains in the second column while the air is permitted to pass through to the vacuum opening, said second column comprising two vertically extending portions separated by a partition and in fluid communication with each otHer via upper and lower openings above and below the partition, respectively, and wherein both portions are exposed to the vacuum source, said partition arranged such that air bubbles from the first column are directed substantially up into only one of the two portions, said baffle means comprising a baffle member located above the said one portion in the path of the rising bubbles, such that the liquid which rises in the said one portion with the bubbles engages the baffle member and falls downwardly as the air continues to float toward the vacuum source, some of this liquid falling into the second portion, and wherein an amount of makeup water flows from the second portion to the first portion through the lower opening, such that flow of at least some liquid is created around the partition, up in the first portion, through the upper opening, and down in the second portion through the lower opening.
 24. A drainage device as claimed in claim 23, said lower opening being shaped to prevent the passage of air bubbles therethrough from the first portion to the second portion.
 25. A drainage device as claimed in claim 24, wherein the said lower opening is directed downwardly from said first portion to said second portion.
 26. A drainage device as claimed in claim 23, wherein said manometer includes a measuring means for measuring the rate of flow of air through the manometer.
 27. A drainage device as claimed in claim 23, including a seal chamber having first and second columns in fluid communication with each other at their lower ends, said seal chamber forming a part of the fluid communication between the vacuum opening and the inlet opening, the first seal chamber column being in fluid communication with the cavity being drained and the second seal chamber column being in fluid communication with said vacuum source, and including a measuring means formed in the seal chamber for measuring the rate of gas flow through the seal chamber, whereby when the pressure in the first seal chamber column exceeds the pressure in the second seal chamber column by a sufficient amount so that gas bubbles can flow from said first seal chamber through said second seal chamber column, said seal chamber measuring means will measure the rate of said gas flow.
 28. A drainage device as claimed in claim 27, including a measuring means in the manometer for measuring the rate of flow of air passing therethrough.
 29. A drainage device as claimed in claim 28, wherein each of said measuring means comprises a flow meter comprising a partition member located in the interior of its respective chamber and having a plurality of holes formed therein, said holes of each flow meter being arranged such that in each chamber, as the associated pressure differential force causing the bubbling in that chamber increases, the number of holes through which the bubbles pass also increases.
 30. A drainage device as claimed in claim 29, wherein the partition member in the manometer extends across the bottom of the second column generally horizontally, said holes being located progressively farther away from the first column, and wherein the partition member in the seal chamber extends horizontally across the bottom of the second column of the seal chamber, and wherein the holes are located progressively farther away from the first column of the seal chamber.
 31. In a device for regulating the pressure within a cavity of a person comprising a trap chamber and an underwater seal chamber, said trap chamber having located at its upper end an inlet opening and an outlet opening, said seal chamber also having located at its upper end an inlet opening and an outlet opening, the seal chamber inlet being in fluid communication with the trap chamber outlet, said trap chamber openings being spaced from each other so that liquid entering the inlet opening can fall downwardly in the trap chamber while gases entering the inlet opening may normally pass through the said chamber outlet to the seal chamber, said seal chamber having first and second vertically extending columns in fluid communication with each other at their lower ends, the seal chamber inlet being located at the upper end of the first column, whereby the first column is exposed to pressure conditions in the trap chamber, and the seal chamber outlet being located at the upper end of the second column whereby the second column is exposed to pressure conditions other than that of the trap chamber; the improvement wherein, said first column includes a baffle means for catching liquids splashed upwardly with air bubbles which pass through the first column of the seal chamber during abnormal conditions when the said other pressure exceeds the trap chamber pressure by a sufficient amount, said baffle means being arranged to direct the liquid downwardly back into the first column while permitting gases to pass by said baffle means and to said trap chamber, the baffle means comprising an inverted cup-shaped separation chamber located at the upper end of the first column directly above the main portion of the first column, and including an enlarged upper reservoir immediately adjacent and in fluid communication with the main portion of the first column adjacent the separation chamber, and the said sealed chamber inlet in fluid communication with the trap chamber being located on the side of the reservoir opposite from the main portion of the first column, whereby the gases which pass said baffle means pass through the enlarged reservoir to the trap chamber.
 32. A drainage device as claimed in claim 31, including a pair of vertically spaced openings between main portion of the first column and the reservoir, the upper of the two openings being positioned so that gases can pass therethrough to the trap chamber and so that some of the liquids which engage the baffle means can pass therethrough to the reservoir, and the lower of the two openings being positioned so that liquid in the reservoir can pass therethrough and rise with the bubbles to the separation chamber.
 33. A drainage device as claimed in claim 31, including a manometer having first and second columns in fluid communication with each other at their lower ends, the first manometer column being exposed to atmosphere and the second manometer chamber being in fluid communication with the second column of the seal chamber, the two second columns thereby forming a common space exposed to said other pressure conditions and a vacuum opening from said common space adapted to be connected to a vacuum source.
 34. A drainage device as claimed in claim 33, wherein said second column of the manometer includes a manometer baffle means which prevents liquid, which may rise in the second column when the said other pressure is less than atmospheric pressure by a sufficient amount, from passing through said vacuum opening of the common space to the vacuum source.
 35. In a drainage device for draining fluids from a cavity comprising an inlet opening adapted to be placed in fluid communication with the cavity to be drained, a vacuum opening adapted to be placed in fluid communication with a vacuum source and with the inlet opening for drawing fluids from the cavity into the device, and a manometer for regulating the vacuum, said manometer comprising first and second columns in fluid communication with each other, said manometer adapted to receive a body of liquid within the first and second columns, the first column being exposed to atmosphere and the second column being exposed to the vacuum source; the improvement wherein, said second column includes two portions in fluid communication with each other, said portions being arranged such that when the pressure of the vacuum source is reduced below atmospheric pressure by a sufficient amount so that air bubbles can pass from said first column upwardly through the second column, said bubbles are substantially confined to only one of said portions, whereby the other portion remains relatively calm so that the level of the liquId in the second column can be easily ascertained by observing the level of the liquid in the said calm other portion.
 36. A drainage device as claimed in claim 35, wherein said tow portions are positioned adjacent each other, separated by a partition which has formed therein an upper opening for said communication between the portions near their upper ends and a lower opening for said fluid communication between said portions near their lower ends.
 37. A drainage device as claimed in claim 36, wherein said lower opening comprises a passage directed downwardly from said one portion to the other portion to form a deflector to prevent air bubbles from passing through said lower openings to the said other portion.
 38. A drainage device as claimed in claim 36, wherein said one portion includes a downwardly concave part above the said upper opening for deflecting downwardly the water which is splashed upwardly by the action of the bubbles passing through the said one portion thereby preventing the water from passing through said vacuum opening. 